Recent Approaches to His-Purkinje System Pacing: Making Pacemakers More “Natural” for the Heart

Did you know that over 3 million people worldwide live with pacemakers? These life-saving devices have come a long way since their invention in the 1950s—but today, researchers are focused on making pacing even more “natural” by tapping into the heart’s own electrical system: the His-Purkinje network. This system is responsible for coordinating the heart’s synchronized contraction, and pacing directly within it could help avoid the long-term risks of traditional pacing methods. Let’s break down the latest advances in His-Purkinje system pacing, including its benefits, challenges, and a promising new technique.

The Problem with Traditional Right Ventricular Apex Pacing (RVAP)

For decades, the most common pacing site has been the right ventricular apex (RVA)—the tip of the right ventricle. RVAP is easy to perform and stable, but long-term use comes with a catch: it disrupts the heart’s natural contraction pattern. Instead of the His-Purkinje system coordinating both ventricles, RVAP triggers the right ventricle first, leading to “desynchronized” pumping.

Studies show this desynchronization can harm heart function over time. For example, a 2016 study in the Anatolian Journal of Cardiology found that patients with high RVAP usage were 2–3 times more likely to develop new heart failure. Another 15-year retrospective study in BMJ Open linked RVAP to “pacing-induced cardiomyopathy,” a condition where the heart weakens due to abnormal electrical stimulation. The key culprit? A widened QRS complex (the part of an ECG that shows ventricular contraction)—longer QRS durations are a strong predictor of heart damage from pacing.

His Bundle Pacing (HBP): A More Physiologic Alternative

To fix this, researchers turned to the His bundle—the “highway” of the heart’s electrical system. Located between the atria and ventricles, the His bundle sends signals to the left and right bundle branches, which then activate the Purkinje fibers and sync the ventricles. Pacing directly at the His bundle (HBP) mimics this natural pathway, resulting in a narrow QRS complex (like a healthy heartbeat) and preserved heart function.

What Is HBP?

HBP is divided into two types:

Selective HBP (S-HBP): The pacemaker lead activates only the His-Purkinje system, producing a QRS wave identical to the heart’s natural rhythm.
Non-Selective HBP (NS-HBP): The lead activates both the His bundle and nearby ventricular muscle, which can cause slightly wider QRS waves but still offers better synchronization than RVAP.

A 2000 study by Deshmukh et al in Circulation was the first to test S-HBP in humans—and the results were promising: patients maintained normal heart contraction and had no QRS widening. Since then, HBP has been shown to improve outcomes for patients with:

Intra-His bundle block: A blockage in the His bundle itself.
Sick sinus syndrome: Irregular heartbeats from a faulty sinoatrial node.
Atrial fibrillation: For patients who need atrioventricular node (AVN) ablation, HBP replaces RVAP and preserves heart function (a 2017 study in Europace found LVEF improved by up to 50% in these patients).

HBP also works as an alternative to cardiac resynchronization therapy (CRT)—a treatment for heart failure with left bundle branch block (LBBB). A 2018 multicenter study in Heart Rhythm found that HBP shortened QRS duration and improved left ventricular ejection fraction (LVEF) more effectively than CRT in some patients.

The Challenges of HBP

While HBP is widely regarded as the most physiologic pacing method, it’s not without hurdles:

Implantation Difficulty: The His bundle is tiny (just a few millimeters long) and surrounded by scar tissue in some patients, making it hard to place leads accurately. Up to 45% of HBP attempts fail, according to a 2008 study in Revista Española de Cardiología.
High Pacing Thresholds: HBP requires more electrical energy to trigger a heartbeat than RVAP, which can drain pacemaker batteries faster.
Risk of Bundle Branch Injury: In 7.8% of cases, HBP leads can damage the His bundle, causing new conduction blocks (per a 2016 study in J Electrocardiol).
Not for Infra-His Block: HBP doesn’t work if the blockage is below the His bundle (in the bundle branches or Purkinje fibers).

Left Bundle Branch Pacing (LBBP): A New Hope

To overcome HBP’s limits, researchers have turned to the **left bundle branch (LBB)—a major branch of the His-Purkinje system that activates the left ventricle. LBBP involves placing a lead directly into the LBB, which:

Produces even narrower QRS waves than HBP.
Has lower pacing thresholds (less energy needed).
Is easier to implant (the LBB is more accessible than the His bundle).

In 2017, Huang et al from the Canadian Journal of Cardiology reported the first successful LBBP implants in humans. Their study of 15 patients found that 13 achieved stable, low-threshold pacing—with no serious complications. The authors note that LBBP could be a game-changer for patients with infra-His block, where HBP fails.

However, LBBP is still in its early stages. The small sample size and lack of long-term data mean researchers need larger randomized trials to confirm its benefits—especially for patients with advanced heart failure or severe scarring of the right ventricular septum.

What’s Next for His-Purkinje Pacing?

The future of cardiac pacing is all about “working with” the heart, not against it. HBP remains the gold standard for physiologic pacing, but LBBP offers a promising alternative for patients where HBP isn’t feasible. Both methods aim to solve the biggest problem with traditional pacing: preserving the heart’s natural synchronization.

As the authors of the original review note: “While HBP is the most physiologic method, its limitations mean we need to explore new approaches like LBBP. The key is to match the pacing strategy to the patient’s anatomy and needs.”

This article is based on a review published in the Chinese Medical Journal (2019) by Li-Ting Cheng, Jun-Meng Zhang, Ze-Feng Wang (Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University), Hui-Kuan Gao (Department of Cardiology, Beijing Friendship Hospital, Capital Medical University), and Yong-Quan Wu (corresponding author). The study analyzed peer-reviewed publications up to July 2018 from PubMed.

doi.org/10.1097/CM9.0000000000000038

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